This invention relates to safety relief valves and, more particularly, to a compact safety relief valve having high volumetric flow.
Heretofore, safety relief valves have typically incorporated a poppet, a spring for biasing the poppet toward a position closing the valve, and various sections or structure within the flow path to support and guide the poppet and spring.
These various items all constrict the flow of the fluid, such as gas, which the valve is intended to control by causing various conditions such as turbulence, cavitation and the formation of one or more vena contractas. In effect, these constrictive conditions give rise to a lower pressure downstream from the position in which they are present. The difference between the upstream and downstream pressures is referred to as pressure drop or .DELTA.P.
Generally speaking, when a medium flows through a restriction, a flow pattern is formed in which the area of flow is less than the area of the opening through which it flows. This results in what is termed a "vena contracta" at the point where the flow velocity is the highest and pressure is at its lowest which further restricts the flow of the medium. If the formation of a vena contracta can be avoided within a valve and can be formed instead outside of the valve in the region in which the valve is intended to vent high pressure, no resultant restriction occurs.
Accordingly, an object of the invention is the provision of an improved pressure relief valve which can be utilized as a safety device to vent fluids, primarily gases, from a higher pressure source such as a tank, vessel, pipe, etc., to a region of lower pressure, such as the atmosphere.
A further object of the invention is the provision of such a pressure relief valve which is particularly well suited to the venting of dangerous pressure levels within transformers of the power transmission type.
A still further object of the invention is the provision of such a pressure relief valve which is adapted to provide high volumetric flow therethrough during pressure venting operation in comparison with the size of the valve.
Another object of the invention is the provision of such a pressure relief valve which provides essentially negligible or zero pressure drop across the valve during venting operation being thus extremely efficient during venting operation.
Another object of the invention is the provision of such a pressure relief valve of the poppet type wherein fluids, such as gas, may flow through the valve during pressure relief thereby without being restricted by the poppet, poppet springs or structure of the valve and without formation of a vena contracta within the valve.
Yet another object of the invention is the provision of such a pressure relief valve which opens a predetermined pressure threshold but closes at a lower pressure value.
Among other objects of the invention may be noted the provision of such a pressure relief valve which provides a novel seal arrangement; which is reliable and long-lasting in operation; which is immersible in fluids without effecting its operation; which can be utilized in corrosive atmospheres; which can be manually operated; and which is simple and economical of manufacture.
Other objects and features will be in part apparent and in part pointed out hereinbelow.